BART passengers at the Rockridge Station exit a train that had been stuck in a tunnel.

BART passengers at the Rockridge Station exit a train that had been stuck in a tunnel.

Photo: Michael Macor, The Chronicle

Image 2 of 27

An inured passenger is taken to an ambulance at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were transported to local hospitals. less

An inured passenger is taken to an ambulance at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters ... more

Photo: Paul Chinn, The Chronicle

Image 3 of 27

Firefighters help a rider.

Firefighters help a rider.

Photo: Paul Chinn, The Chronicle

Image 4 of 27

Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. Photo: Courtesy @jess_flores / Instagram Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. less

Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. Photo: Courtesy @jess_flores / Instagram Oakland firefighters respond to ... more

Photo: Courtesy Of Jessica A. Flores

Image 5 of 27

Image 6 of 27

Paramedics wheel an injured passenger to an ambulance at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were transported to local hospitals. less

Paramedics wheel an injured passenger to an ambulance at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several ... more

Photo: Paul Chinn, The Chronicle

Image 7 of 27

An inured passenger is put into an ambulance at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were transported to local hospitals. less

An inured passenger is put into an ambulance at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters ... more

Photo: Paul Chinn, The Chronicle

Image 8 of 27

Firefighters treat injured passengers at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were transported to local hospitals. less

Firefighters treat injured passengers at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were ... more

Photo: Paul Chinn, The Chronicle

Image 9 of 27

Police close down the Rockridge BART station in Oakland, Ca., on Wednesday Dec. 4, 2013, after smoke onboard a BART train was detected which caused a train to become stuck in the Caldecott tunnel between Orinda and Rockridge. less

Police close down the Rockridge BART station in Oakland, Ca., on Wednesday Dec. 4, 2013, after smoke onboard a BART train was detected which caused a train to become stuck in the Caldecott tunnel between Orinda ... more

Photo: Michael Macor, The Chronicle

Image 10 of 27

Image 11 of 27

Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. Photo: Courtesy @jess_flores / Instagram Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. less

Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. Photo: Courtesy @jess_flores / Instagram Oakland firefighters respond to ... more

Photo: Courtesy Of Jessica A. Flores

Image 12 of 27

Firefighters carry an injured passenger from the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were transported to local hospitals. less

Firefighters carry an injured passenger from the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were ... more

Photo: Paul Chinn, The Chronicle

Image 13 of 27

A paramedic assists a passenger who arrived on a rescue train at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were transported to local hospitals. less

A paramedic assists a passenger who arrived on a rescue train at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. ... more

Photo: Paul Chinn, The Chronicle

Image 14 of 27

Fire and rescue personnel at the Rockridge BART station in Oakland, Ca., on Wednesday Dec. 4, 2013, after smoke onboard a BART train was detected which caused a train to become stuck in the Caldecott tunnel between Orinda and Rockridge. less

Fire and rescue personnel at the Rockridge BART station in Oakland, Ca., on Wednesday Dec. 4, 2013, after smoke onboard a BART train was detected which caused a train to become stuck in the Caldecott tunnel ... more

Photo: Michael Macor, The Chronicle

Image 15 of 27

Image 16 of 27

A BART commuter comforts a fellow passenger after the train they were on pulled into the Rockridge Station in Oakland.

A BART commuter comforts a fellow passenger after the train they were on pulled into the Rockridge Station in Oakland.

Photo: Paul Chinn, The Chronicle

Image 17 of 27

An injured passenger is treated by firefighters at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were transported to local hospitals.

An injured passenger is treated by firefighters at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several

Stranded passengers seek information with their mobile phones at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were transported to local hospitals. less

Stranded passengers seek information with their mobile phones at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. ... more

Photo: Paul Chinn, The Chronicle

Image 19 of 27

A police officer removes emergency tape at the Rockridge BART station in Oakland, Calif. when the station reopened on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were transported to local hospitals. less

A police officer removes emergency tape at the Rockridge BART station in Oakland, Calif. when the station reopened on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills ... more

Photo: Paul Chinn, The Chronicle

Image 20 of 27

Image 21 of 27

A firefighter helps passengers arriving on a rescue train at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. Several commuters were transported to local hospitals. less

A firefighter helps passengers arriving on a rescue train at the Rockridge BART station in Oakland, Calif. on Wednesday, Dec. 4, 2013 after a westbound train became stranded in the Berkeley Hills tunnel. ... more

Photo: Paul Chinn, The Chronicle

Image 22 of 27

Firefighters aid a passenger, one of nearly a dozen injured when the BART train broke down.

Firefighters aid a passenger, one of nearly a dozen injured when the BART train broke down.

Photo: Paul Chinn, The Chronicle

Image 23 of 27

Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. Photo: Courtesy @jess_flores / Instagram Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. less

Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. Photo: Courtesy @jess_flores / Instagram Oakland firefighters respond to ... more

Photo: Courtesy Of Jessica A. Flores

Image 24 of 27

Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. Photo: Courtesy @jess_flores / Instagram Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. less

Oakland firefighters respond to passengers at Rockridge BART station suffering with medical problems from a train stuck in a BART tunnel. Photo: Courtesy @jess_flores / Instagram Oakland firefighters respond to ... more

Photo: Courtesy Of Jessica A. Flores

Image 25 of 27

Image 26 of 27

Image 27 of 27

BART breakdown just latest problem for aging fleet

1 / 27

Back to Gallery

The beleaguered BART system suffered another high-profile breakdown Wednesday when the emergency brakes on a train speeding through the Berkeley hills tunnel locked up, filling the cars with fumes.

The fumes, which some passengers mistook for smoke, prompted several riders to seek medical treatment after being stuck onboard the crippled train for an hour, officials said.

BART officials said a short circuit caused the train's emergency braking system - technology from the 1980s - to engage, which is relatively rare, having happened just three times this year, BART spokeswoman Alicia Trost said.

President Trump addresses nation after mass shooting at Florida SchoolWhite House

While the breakdown was uncommon, it was just the latest in a series of incidents - from strikes to contract disputes to computer failures - to bedevil the transit system and its 400,000 daily passengers.

"These types of things make me want to drive my car to work," said Paloma Garcia, a passenger on the stalled train.

Late in the day, BART officials were still investigating the cause of the incident, which occurred about 8:30 a.m. after the westbound Pittsburg/Bay Point-line train, packed with 700 passengers, pulled out of the Orinda Station and entered the 3.2-mile tunnel.

Aging trains

But the system's aging trains - with an average tenure of more than 33 years, with many older than 40 years - are the most common reason for delays.

A Chronicle analysis in 2012 of delays lasting 15 minutes or more found that troubles with trains were responsible for 25 percent of delays. Brake failures were a leading cause, along with problems with propulsion systems, automated train controls, doors and electrical systems.

"It's part of our investment needs," Trost said. And while the transit system has ordered a new fleet of rail cars and has plans for a new train-control system and rail-maintenance facility, it will need billions of dollars more for upkeep and modernization of the system.

The transit agency will probably ask voters, many of whom are growing increasingly frustrated by BART's plethora of problems, to approve new taxes or bonds to pay for those improvements.

Trost said the train operator recognized the problem Wednesday morning, notified BART's central control, walked through the train and opened some doors for ventilation, and released the locked-up brakes.

Strong odor

When the brakes locked up, she said, they released a small amount of light smoke - or dust - but also a strong odor. Battalion Chief Melinda Drayton of the Oakland Fire Department said the noxious fumes were brake dust.

When the train finally began moving again and pulled into the Rockridge Station in Oakland at 9:30 a.m., firefighters treated 11 people for medical problems, nine of whom were taken to hospitals, Drayton said. The patients were treated for dizziness, shortness of breath and nausea and were expected to recover, authorities said.

BART also switched on a ventilation system in the tunnel that causes gates to lower at the Orinda portal. When the tunnel was cleared, one of the gates failed to lift automatically and needed to be raised by hand. That forced BART to run alternating trains on a single track, slowing them even more.